Nanocellulose Bulk Material Prepared by Steam Treatment and Hot Press Molding: Material Processing and Machining Test

Nanocellulose (NC) has been spotlighted as a new building block of future materials since it has many advantages, such as being lightweight and environment-friendly and having high mechanical properties and heat resistance. However, the use of NC requires an upscale manufacturing process to maintain its advantageous properties. Herein, the process of assembling NC into a macro-scale bulk material was developed through a combination of steam treatment and hot press molding. The steam treatment was applied to an NC paste to energize the hydroxyl groups in the cellulose, followed by two stages of hot press molding, which helped in the self-assembly of NC without adhesives. Cellulose nanocrystals were used as the NC, and circular disk shape specimens were prepared. The mechanical properties of the prepared bulk material were higher than typical engineering plastics. In addition, an end mill machining test of the NC bulk material showed its machinability. This paper showed the processing feasibility of NC bulk material, which can substitute plastics.

Structural Design of Groove and Micro-Blade of the End Mill Based on Bionics

The existing end mill is hard to balance the tool rigidity, heat dissipation and chip evacuation. In this study, the geometries of groove and micro-blade of the end mill machining titanium are optimized, through imitating the corn leaf’s tooth based on bionics. The peripheral cutting edge is composed of linear first rake, parabolic second rake and rear face. The chip-hold groove is composed of parabolic main groove and cubic curve vice groove. The cutting process of straight tooth and designed composite tooth are simulated by constructing the two-dimensional orthogonal cutting model using ABAQUS. The results show that: compared to the straight tooth, the designed composite tooth inhibits the generation of serrated chip, and the fluctuations of cutting force are smaller, the squeezing effect on the machined surface is weaker.

Research on the Tool Wear Mechanism of Cemented Carbide Ball End Mill Machining Titanium Alloy

In order to achieve the high efficiency machining of titanium, the cutting force model is verified through the cutting experimental platform in machining cant and curved surface with ball end milling. And then the influence of cutting parameters and surface curvature on cutting force and tool wear are investigated. Finally, the prediction model of tool wear is established based on the orthogonal test and the least square method. This study proposes that the tool wear and each tooth feeding have a major impact on cutting force and that the convex surface from a small curvature to larger and the concave surface from a large curvature to smaller can effectively improve the life of tool in machining curved surface.